2.0.0

arrow-core/arrow.core/None

None

object None : Option<Nothing>

Functions

inline fun <A> Option<A>.combine(other: Option<A>, combine: (A, A) -> A): Option<A>

operator fun <A : Comparable<A>> Option<A>.compareTo(other: Option<A>): Int

inline fun filter(predicate: (Nothing) -> Boolean): Option<Nothing>

Returns this

$option if it is nonempty '''and''' applying the predicate $

p to this

$option's value returns true. Otherwise, return $

none.

filterIsInstance

inline fun <B> Option<*>.filterIsInstance(): Option<B>

Returns an Option containing all elements that are instances of specified type parameter B.

inline fun filterNot(predicate: (Nothing) -> Boolean): Option<Nothing>

Returns this

$option if it is nonempty '''and''' applying the predicate $

p to this

$option's value returns false. Otherwise, return $

none.

inline fun <B> flatMap(f: (Nothing) -> Option<B>): Option<B>

Returns the result of applying

$f to this $

option's value if this

$option is nonempty. Returns $

none if this

$option is empty. Slightly different from map in that $

f is expected to return an

$option (which could be $

none).

fun <A> Option<Option<A>>.flatten(): Option<A>

inline fun <R> fold(ifEmpty: () -> R, ifSome: (Nothing) -> R): R

inline fun <T> Option<T>.getOrElse(default: () -> T): T

Returns the option's value if the option is nonempty, otherwise return the result of evaluating default.

fun getOrNull(): Nothing?

Returns the encapsulated value A if this instance represents Some or null if it is None.

fun isNone(): Boolean

Returns true if the option is None, false otherwise.

fun isSome(): Boolean

Returns true if the option is Some, false otherwise.

inline fun isSome(predicate: (Nothing) -> Boolean): Boolean

Returns true if this option is nonempty '''and''' the predicate

$p returns true when applied to this $

option's value. Otherwise, returns false.

inline fun <B> map(f: (Nothing) -> B): Option<B>

Returns a [Some<

$B>] containing the result of applying $

f to this

$option's value if this $

option is nonempty. Otherwise return $none.

inline fun onNone(action: () -> Unit): Option<Nothing>

The given function is applied as a fire and forget effect if this is a None. When applied the result is ignored and the original None value is returned

inline fun onSome(action: (Nothing) -> Unit): Option<Nothing>

The given function is applied as a fire and forget effect if this is a some. When applied the result is ignored and the original Some value is returned

inline fun <A> Option<A>.recover(recover: SingletonRaise<None>.() -> A): Option<A>

Recover from any None if encountered.

inline fun <L> toEither(ifEmpty: () -> L): Either<L, Nothing>

fun toList(): List<Nothing>

fun <K, V> Option<Pair<K, V>>.toMap(): Map<K, V>

open override fun toString(): String